Network Topologies | Class 12

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Introduction to Network Topology:

Network topology defines the arrangement of devices and the way they communicate in a network. It shapes the network’s efficiency, fault tolerance, and scalability. Different topologies offer distinct advantages and trade-offs.

Types of Network Topologies:

  1. Bus Topology:

    Bus topology is a type of network topology in which all devices in the network are connected to a single central cable, known as the “bus” or backbone. This central cable acts as a shared communication medium through which data is transmitted between devices. Each device on the network can receive and transmit data, but the data travels along the bus and is accessible by all devices connected to it.

    Fig : Bus Topology

    Features of Bus Topology:

    1. Single Backbone: All devices are connected to a single central cable, simplifying the network layout.

    2. Terminators: The bus topology requires terminators at both ends of the central cable to prevent signal reflection.

    3. Simple Design: The topology is easy to install and requires minimal cabling.

    4. Low Cost: It typically requires less cabling compared to other topologies, making it cost-effective for small networks.

    5. Scalability: Adding or removing devices is relatively straightforward, making it moderately scalable.

    Advantages of Bus Topology:

    1. Easy Installation: Setting up a bus topology is simple and requires less cable compared to some other topologies like star or ring.

    2. Cost-Effective: Due to the reduced cabling and hardware requirements, bus topology is cost-effective for smaller networks.

    3. Direct Communication: Devices can directly communicate with each other over the central bus without needing intermediary devices.

    4. Moderate Scalability: Adding or removing devices doesn’t disrupt the entire network, making it moderately scalable for small to medium-sized networks.

    5. Suitable for Small Networks: Bus topology is well-suited for small networks where communication needs are relatively simple.

    Disadvantages of Bus Topology:

    1. Single Point of Failure: If the central bus cable fails, the entire network can be brought down.

    2. Limited Cable Length: The length of the central bus is limited, which can impact the size of the network.

    3. Performance and Congestion: As more devices are added to the network, the overall performance can degrade, and network congestion can occur.

    4. Difficult Troubleshooting: Identifying faults or cable breaks can be challenging since the entire network can be affected by a single issue.

    5. Collision Possibilities: In networks with heavy traffic, data collisions can occur when multiple devices try to transmit data simultaneously, leading to data loss and retransmissions.

    6. Limited Privacy and Security: Since all devices share the same communication medium, it can be easier for unauthorized users to intercept data.Ring Topology:

  2. Star Topology:

    Star topology is a network setup where all devices are connected to a central hub or switch. Instead of connecting devices directly to each other, they all connect to this central point. The central hub acts like a traffic controller, managing communication between devices.

    Fig : Star Topology

    Features of Star Topology:

    1. Central Hub: All devices are linked to a central hub, making it the focal point of the network.

    2. Point-to-Point: Devices communicate with the hub directly, creating a point-to-point connection.

    3. Easy Setup: Setting up and expanding the network is simple as you only need to connect or disconnect devices from the hub.

    Advantages of Star Topology:

    1. Centralized Management: The hub provides easy control and monitoring of the network.

    2. Isolation: Issues with one device typically don’t affect the rest of the network, enhancing reliability.

    3. Easy Troubleshooting: Identifying and resolving problems is simpler because the hub isolates issues.

    4. Scalability: Adding more devices is straightforward by connecting them to the hub.

    Disadvantages of Star Topology:

    1. Dependence on Hub: If the hub fails, the entire network can go down.

    2. Single Point of Failure: The hub is a critical component; if it malfunctions, the whole network is affected.

    3. Cost: Setting up the central hub and cabling can be more expensive initially.

    4. Complexity: As the network grows, managing multiple connections to the hub can become complex.

  3. Ring Topology:

    Ring topology is a network configuration where each device is connected directly to exactly two other devices, creating a circular pathway for data to travel. Data flows in one direction through the ring, passing through each device until it reaches its destination.

    Fig : Ring Topology

    Features of Ring Topology:

    1. Circular Connection: Devices are connected in a closed loop, forming a ring-like structure.

    2. Unidirectional Data Flow: Data travels in one direction around the ring from one device to the next.

    3. Token Passing: Token is used to regulate data transmission around the ring.

    Advantages of Ring Topology:

    1. Orderly Data Flow: Data moves in a predictable sequence from one device to another, reducing collisions.

    2. Equal Access: Each device has equal access to the network, as there’s no central hub controlling traffic.

    3. Simple Configuration: Setting up a ring topology is relatively straightforward.

    Disadvantages of Ring Topology:

    1. Single Point of Failure: If one device or connection fails, the entire network can be disrupted.

    2. Network Isolation: Devices before and after a failed device are isolated, affecting their connectivity.

    3. Limited Scalability: Adding or removing devices can disrupt the entire network.

    4. Data Loss Risk: Data integrity is at risk if a device fails or if there are issues in the ring.

  4. Mesh Topology:

    Mesh topology is a network configuration where every device is directly connected to every other device. In a mesh network, devices are like individual nodes that create a web of direct connections, forming a highly interconnected structure.

    Fig : Mesh Topology

    Features of Mesh Topology:

    1. Full Connectivity: Every device has a direct link to all other devices in the network.

    2. Redundancy: Multiple paths exist for data transmission, increasing reliability.

    3. No Central Hub: There’s no single central point of control or failure.

    Advantages of Mesh Topology:

    1. Robustness: Redundant connections ensure that if one path fails, data can still travel through other routes.

    2. Reliability: The network remains operational even if some devices or links fail.

    3. High Performance: Multiple paths can lead to faster data transmission and reduced congestion.

    4. Security: Data can be sent directly between specific devices, enhancing privacy.

    Disadvantages of Mesh Topology:

    1. Complexity: Setting up and maintaining numerous connections can be complex and costly.

    2. Resource Intensive: More cables and ports are required, potentially leading to higher costs.

    3. Scalability Challenges: Expanding the network with additional devices can become intricate.

    4. Maintenance Difficulty: Troubleshooting and identifying issues within the dense network can be challenging.

In conclusion, network topology plays a crucial role in determining the structure, efficiency, and reliability of computer networks. Different topologies, offer varying degrees of simplicity, scalability, and fault tolerance.

Sailendra Shrestha
WRITTEN BY

Sailendra Shrestha

Student

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